UNIVERSITY  OF  MISSOURI 
COLLEGE  OF  AGRICULTURE 

Agricultural  Experiment  Station 

COLUMBIA,  MISSOURI,  OCTOBER,  1915 

CIRCULAR  NO.  78 


THE  CONTROL  OF  SOIL  WASHING 

M.  F.  Miller 

Soil  washing  is  the  greatest  single  source  of  loss  on  many  rolling 
lands.  It  is  greater  than  the  loss  of  plant  food  thru  cropping.  The 
washing  oft  of  the  surface  soil  during  a  single  season  may  remove 


Cut  in  One  Season 

The  uprooted  tree  on  the  reader's  left  stood  on  the  right  bank  of  a 
small  gully.  One  season  of  exceptional  rainfall  cut  so  deep  a  ditch  that 
only  an  expensive  system  of  dams  ivill  stop  it. 

as  much  organic  matter  as  will  be  replaced  by  the  turning  under  of  two 
or  three  clover  crops.  A  single  rain  may  form  gullies  which  it  will 
require  years  to  repair.  And  the  injury  to  the  land  itself  is  only  a 
part  of  the  story.  The  tilling  of  our  smaller  streams  with  silt  and  the 

(1) 

JlaiE  hhfalwj  If  kiml 

iHiiq  ‘ 


2  MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 


great  injury  that  is  done  navigation  by  the  clogging  of  our  large  water 
courses  with  this  eroded  material  is  another  very  important  phase 
of  the  subject,  when  the  country  as  a  whole  is  considered.  The 
present  season  has  certainly  emphasized,  in  the  minds  of  all  observing 
farmers,  the  great  havoc  which  may  be  caused  by  soil  washing. 


1 


Fig.  1.  Neglected  Gullies  on  Rolling  Upland 

This  could  have  been  easily  prevented.  The  soil  here  is  good,  but  the 
value  of  the  land  on  this  field  has  depreciated  many  dollars  per  acre  as  a 
result  of  these  gullies. 

There  would  be  little  need  of  calling  attention  to  these  matters 
if  it  were  not  for  the  fact  that  a  large  share  of  such  damage  is 
preventable.  The  great  need  of  soil  conservation  is  more  strongly 
emphasized  each  year  and  in  no  way  is  greater  care  needed  than  in 
the  prevention  of  soil  erosion.  While  it  is  a  very  serious  national 
problem,  it  is  a  matter  over  which  the  government  or  the  state  has 
little  control.  It  is  a  problem  for  the  individual  land  owner.  Public 
sentiment  should  be  awakened  to  the  seriousness  of  the  problem  and 
the  land  owner  brought  to  realize  the  importance  of  persistent  efforts 
of  control. 


KINDS  OF  WASHING 

There  are  two  kinds  of  soil  washing — sheet  washing  and  gullying. 
Sheet  washing  is  the  washing  of  the  immediate  surface  soil  without 
the  formation  of  appreciable  gullies.  This  is  less  noticeable  than 
gullying,  but  almost  as  injurious,  since  it  removes  almost  as  large 


THE  CONTROL  OF  SOIL  WASHING 


3 


amounts  of  soil  of  the  best  surface  layers,  including  large  quantities 
of  organic  matter.  Gullying  has  the  disadvantage  of  leaving  the  field 
rough  and  a  gully  once  started  continues  to  enlarge  unless  remedial 
measures  are  adopted.  Sheet  washing  is  most  common  in  freshly 
tilled  land,  such  as  corn  land,  where  on  sharp  slopes  as  much  as  an 
inch  of  the  best  surface  soil  may  be  removed  during  a  single  heavy 
rain.  The  gullying  usually  starts  in  tilled  land  but  unless  stopped  con¬ 
tinues  indefinitely. 


CAUSES  OF  SOIL  WASHING 

A,s  long  as  land  is  kept  in  timber  or  in  thick-growing  vegetation, 
as  in  its  virgin  state,  the  rate  of  surface  loss  from  the  average  soil 
by  erosion,  is  less  than  the  rate  of  accumulation  by  rock  weathering. 


Fig.  2.  Corn  Ruined  hy  Accumulation  of  Top  Soil 

An  accumulation  of  two  or  three  feet  of  top  soil  on  the  lower  ground 
of  a  cornfield,  completely  ruined  the  corn  on  the  area  covered.  This  means 
a  large  loss  to  the  average  soil  on  the  field. 

When  the  land  is  put  in  cultivation,  erosion  is  greatly  increased  and 
the  rate  of  loss  is  then  far  greater  than  the  rate  of  soil  formation. 
It  is,  however,  when  the  land  is  in  tilled  crops  that  the  greatest  loss 
occurs.  Every  farmer  realizes  the  washing  which  accompanies  corn¬ 
growing. 


4 


MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 


Careless  Culture.  Careless  culture  is  undoubtedly  productive  of  the 
greatest  losses.  Where  washes  once  start  they  invariably  become  worse 
rather  than  better  if  the  land  is  kept  in  cultivation. 

Shallow  Plowing.  Shallow  plowing  is  one  of  the  causes  of  washing 
which  usually  accompanies  careless  farming.  Where  land  is  plowed 
shallow  the  water  quickly  penetrates  to  the  depth  of  this  loose  soil 
and  if  the  rain  continues  to  fall  more  rapidly  than  it  can  be  absorbed 
by  the  compact  soil  beneath,  the  run-off  will  carry  with  it  some  of 
this  loose  surface  soil.  If  the  rainfall  is  very  heavy  the  shallow  surface 
soil  may  be  entirely  removed  on  the  steeper  slopes.  If  the  plowing 
is  deep,  most,  if  not  all,  of  the  water  will  be  absorbed  and  washing 
greatly  decreased. 


Pig.  3.  Opened  with  Road  Scraper 

This  rock  road  had  been  covered  several  inches  deep  with  the  good 
top  soil  from  adjoining  fields. 


Insufficient  Organic  Matter.  One  of  the  important  causes  con¬ 
tributing  to  washing  is  a  low  supply  of  organic  matter  in  the  soil. 
Soils  with  much  organic  matter  absorb  the  water  more  rapidly  and 
the  organic  matter  also  tends  to  bind  the  particles  together  and  prevent 
washing.  For  this  reason  old  lands,  low  in  organic  matter,  wash  worse 
than  new  lands.  Likewise  corn  land  prepared  from  stubble  ground 
washes  worse  than  corn  land  prepared  from  sod. 


THE  CONTROL  OF  SOIL  WASHING 


5 


Clay  Soil  Absorbs  Water  Slowly.  The  texture  of  the  soil  is  also 
an  important  factor  in  determining  the  amount  of  washing.  A  sandy 
soil  absorbs  water  rapidly  and  washes  very  little.  A  clay  soil,  on  the 
other  hand,  absorbs  water  slowly  and  is  particularly  subject  to  gully¬ 
ing.  The  intermediate  soils  such  as  fine  sandy  loams  and  silts  are 
most  affected  by  sheet  washing  but  they  will  also  gully  badly. 

Frequent  Heavy  Rains.  Probably  the  most  important  single  cause 
of  soil  washing  is  the  occurrence  of  frequent  torrential  rains,  par¬ 
ticularly  when  the  land  is  being  cultivated.  A  continental  climate, 
such  as  that  found  in  Missouri,  must  invariably  have  a  rainfall  of 
unequal  distribution,  with  many  torrential  rains  and  therefore  a  greater 
amount  of  serious  soil  erosion  than  occurs  in  those  regions  more 
favorably  situated  in  this  respect. 

CONTROLLING  WASHING 

In  controlling  washing,  as  in  controlling  disease,  preventive 
measures  are  more  important  than  remedies.  Where  washing  has 
already  taken  place,  of  course  remedial  measures  alone  are  left.  If 
the  washing  has  been  long  continued,  however,  the  remedies  are  costly 
and  it  is  rare  that  the  land  can  be  put  into  as  good  condition  as  it 
was  in  originally,  even  with  great  expense.  There  are  few  cases  where 
the  old  saying  that  “a  stitch  in  time  saves  nine”  is  more  applicable 
than  in  the  handling  of  land  to  prevent  washing. 

PREVENTIVE  MEASURES 

A  crop  rotation  which  leaves  the  land  bare  as  short  a  time  as 
possible  is  the  most  fundamental  preventive  measure.  Naturally  corn 
must  be  grown  on  most  farms  but  there  are  very  few  where  corn 
must  be  grown  over  one-third  of  the  time  on  the  individual  fields 
and  where  all  the  stalk  land  must  lie  bare  during  the  fall,  winter,  and 
spring. 

Winter  Cover  Crops.  The  use  of  winter  cover  crops  such  as  rye 
will  go  a  long  way  in  preventing  the  washing  of  the  fall,  winter,  and 
spring  rains.  The  man  who  has  never  tried  a  crop  like  rye  will  be 
surprised  at  the  effect  of  the  fibrous  roots  of  this  crop  in  holding  the 
soil.  Other  crops  which  may  be  used  to  advantage  are  wheat,  barley, 
and — in  the  southern  half  of  the  state — crimson  clover.  The  use  of 
such  crops  not  only  means  a  saving  of  soil  but  also  the  addition  of 
organic  matter  or  humus — a  substance  badly  needed  in  most  lands 
which  are  inclined  to  wash. 

Deep  Plowing.  The  second  general  principle  of  prevention  is  tiiat 
of  deep  plowing,  the  object  being  to  provide  a  deeper  water  reservoir 


6  MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 


to  hold  the  heavy  rains  and  to  cause  a  rapid  absorption  of  the  water. 
Fortunately,  in  Missouri,  plowing  is  generally  deeper  than  in  the 
southern  states  where  washing  is  most  destructive.  There  is,  how¬ 
ever,  still  much  room  for  improvement  in  many  cases.  Rolling  land 
should  rarely  be  plowed  less  than  five  inches  deep  and  from  seven 
to  nine  inches  is  usually  better.  Land  plowed  eight  inches  deep  can 
be  expected  to  absorb  practically  twice  as  much  water  as  that  plowed 


Fig.  4.  Use  of  Rye  to  Prevent  Washing 

The  bare  eondition  of  the  soil  shown  in  the  upper  pieture  is  common 
every whei'e  in  the  corn  sections  of  Missoin'i.  The  lower  picture  shows  how 
this  may  he  remedied  and  washing  inevented  by  the  use  of  rye  as  a  winter 
cover  crop.  Other  fall-sown  cereals  will  also  answer.  In  addition  to  re¬ 
ducing  icashi)ig.  much  valuable  pasture  is  secured. 

four  inches  deep,  at  least  for  the  first  few  weeks  after  plowing,  and 
the  rains  which  will  be  heavy  and  torrential  enough  to  cause  washing 
with  the  deeper  plowing  will  be  much  less  frequent. 

Contour  Farming.  A  preventive  measure  which  the  Missouri 
farmer  on  rolling  land  must  sooner  or  later  learn  to  apply  is  that  of 


THE  CONTROL  OF  SOIL  WASHING 


/ 


contour  farming,  that  is,  farming  the  land  around  or  across  the  slope, 
rather  than  with  the  slope.  Where  furrows  run  up  and  down  the  slope 
washing  is  greatly  increased.  In  the  southern  states  this  principle  is 
almost  universally  practised  in  the  rolling  sections.  Where  land 
washes  badly,  it  is  more  important  to  cultivate  corn  across  the  slope 
only,  than  it  is  to  check  the  corn  and  plow  both  ways.  The  man  who 
■drills  his  corn  with  the  slope  because  the  field  is  somewhat  longer 
in  that  direction  and  therefore  increases  very  materially  the  washing 
-of  the  land  is  certainly  not  doing  all  he  can  to  maintain  soil  produc¬ 
tiveness.  Of  course  on  many  rolling  fields,  of  considerable  size,  the 
land  may  slope  in  dififerent  directions  in  diflferent  parts  of  the  field 


Fig.  5.  Washing  Increased  hy  Direction  of  Rows 

Land  should  he  planted  and  eultivated  across  the  slope  or  around  the 
hill,  if  practicable,  especially  where  the  soil  is  of  a  nature  to  wash  badly. 


and  under  extensive  systems  of  farming  it  is  difficult  to  divide  such 
uelds  so  that  this  so-called  “contour  farming”  may  be  practised.  As 
agriculture  becomes  more  intensive,  however,  more  and  more  attention 
should  be  given  to  this  practise.  It  is  unlikely  that  the  terracing  of 
lands  which  is  so  common  in  the  southern  states  will  have  a  very 
important  place  in  Missouri  agriculture  but  there  are  many  farms 
in  the  rolling  sections  where  such  a  system  would  be  economical  under 
more  intensive  systems  of  farming. 

Organic  Matter  in  Soil.  A  fourth  general  preventive  measure  in 
controlling  washing  is  that  of  maintaining  organic  matter  in  the  soil. 
Soils  low  in  organic  matter  wash  much  more  than  those  high  in  organic 


8  MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 

matter.  This  is  due  to  the  fact  that  soils  high  in  organic  matter 
absorb  water  more  rapidly  than  those  which  are  low  in  this  material, 
while  the  presence  of  organic  matter  also  aids  in  binding  the  soil 
particles  together,  thus  preventing  washing.  The  farmer  who  main¬ 
tains  organic  matter  by  crop  rotation,  manuring,  and  the  growing  of 
cover  crops  will  suffer  little  from  soil-washing.  ' 

STOPPING  WASHES 

The  remedies  for  soil  washing  are  mostly  included  under  the  vari¬ 
ous  methods  of  filling  gullies.  Many  means  are  employed,  different 


Fig.  6.  Straw  Saves  Soil 

The  soil  is  deposited  in  the  straw  and  the  gully  gradually  filled. 


methods  being  applicable  under  diff  erent  conditions.  Whatever  method 
is  adopted,  however,  constant  care  is  necessary  if  the  best  results  are 
to  be  secured. 

Straw  for  Small  Gullies.  In  the  case  of  certain  soils  where  small 
gullies  persist  in  starting  in  corn  fields,  wheat  fields,  and  even  in 
pastures  and  meadows  during  the  fall  and  winter,  the  immediate  use 
of  straw  or  similar  material  is  necessary  to  stop  them.  In  such  cases 
constant  attention  is  required  and  these  small  gullies  should  never  be 
allowed  to  reach  any  considerable  size.  This  is  particularly  true  in 


THE  CONTROL  OF  SOIL  WASHING 


pastures  or  meadows,  where  it  is  often  considered  that  the  land  is  pro¬ 
tected  by  the  grass  and  no  attention  need  be  given  it.  Gullies  starting 
in  drainage  ways  or  in  cattle  paths  on  such  fields  often  develop  to 
tremendous  size. 

Drag  Dirt  and  Sow  Sorghum.  In  cultivated  fields  where  gullies  start 
in  the  spring  or  early  summer,  a  very  good  plan  is  to  drag  in  some 
dirt  and  sow  sorghum  thickly.  If  the  sorghum  gets  started  before 
a  heavy  rain  comes  it  will  hold  the  soil  and  make  it  possible  to  harrow 
and  cultivate  across  these  gullies  during  the  season,  thus  dragging  in 
dirt  which  will  entirely  fill  them.  Gullies  a  foot  deep  and  two  or 
three  feet  wide  may  be  quite  effectively  filled  in  this  way. 


Fig.  7.  Sorghum  Stops  Washes 

It  is  especially  efficient  where  rather  large  gullies  are  first  worked  in 
and  sorghum  soum  on  the  loose  soil. 

Fill,  Plow,  Harrow,  Seed.  Gullies  a  foot  or  two  in  depth  and  from 
two  to  four  feet  wide  can  well  be  stopped  with  straw  or  debris,  and 
dirt  plowed  on  top  of  this  during  the  late  winter  or  spring  months  so 
as  to  fill  them  as  nearly  as  possible.  They  should  then  be  harrowed 
over  and  top  dressed  with  manure  containing  timothy  hay  or  barn 
floor  sweepings,  or  if  these  are  not  available  sow  timothy  seed  with 
the  manure.  Some  alfalfa,  bluegrass,  and  red  top  seed  may  often 
be  added  with  the  timothy  to  advantage.  Where  straw  of  debris  is 
riot  available  such  gullies  may  be  merely  plowed  in,  harrowed,  manured, 
and  seeded  to  grass,  as  mentioned  above,  with  good  results.  Sorghum 
may  also  be  seeded  on  this  filled-in  soil  to  hold  the  land  during  the 
summer  and  fall  and  the  grass  seeded  the  following  spring. 


10  MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 

Brush,  Logs,  Stumps  for  Large  Gullies.  Gullies  which  are  too  large 
to  plow  in  easily,  offer  a  very  serious  and  expensive  problem 
in  filling.  Brush,  logs,  and  stumps  may  be  used  in  hill¬ 
ing  them  and  where  properly  handled  these  prove  very  effective. 
Stones  are  also  sometimes  used  but  they  are  of  little  value.  Brush 
should  always  be  piled  with  the  tops  up  stream.  In  the  case  of  hne 
brush,  particularly,  it  is  best  to  stake  it  down  at  intervals.  Where 
available,  osage  orange  and  cedar  furnish  the  best  of  brush  to  use. 


Fig.  8.  Once  a  Beep  Gully,  Now  Level  Enough  to  Farm  Over 

There  are  few  washes  which  proper  measures  of  handing  will  not  com¬ 
pletely  fill. 


If  brush  is  mixed  with  straw  it  is  usually  more  satisfactory  than  where 
used  alone  and  the  more  compact  it  can  be  made  the  better.  Loose 
brush  is  of  little  value. 

Brush  Dam.  The  use  of  various  sorts  of  dams  in  the  stopping  of 
gullies  is  becoming  common.  For  small  gullies  a  row  of  stakes  driven 
across  and  straw  piled  above  answers  in  some  cases,  but  these  must  be 
continually  watched.  For  larger  gullies  a  dam  of  brush  gives  fair 
results  when  properly  built.  It  is  best  to  build  it  of  green  brush  with 
leaves  on  it,  if  cedar  is  not  available,  laying  the  longer  pieces  on  the 
bottom  with  the  tops  up  stream,  then  piling  the  shorter  pieces  on  top. 


THE  CONTROL  OF  SOIL  WASHING 


11 


For  best  results  the  brush  should  be  mixed  with  straw  and  staked  down. 
It  should  be  tightly  packed  and  left  lowest  in  the  middle  to  prevent 
cutting  around  the  edges. 

Concrete  Dams.  Reinforced  concrete  dams  are  quite  satisfactory 
for  particular  locations,  especially  for  those  large  gullies  which  are 
deep  and  narrow.  Such  dams  should  be  from  six  to  twelve  inches 
thick,  depending  on  the  size  and  depth  of  the  gully.  The  proper 
reinforcing  of  such  a  dam  is  very  important,  iron  rods  of  good  weight 
being  essential  in  the  larger  dams  and  heavy  wires  in  the  smaller 
ones.  The  middle  should  be  left  lower  than  the  edges  and  a  spillway 
provided  with  a  concrete,  stone,  or  brick  apron  placed  in  the  bottom 
’  of  the  gully  to  prevent  cutting  by  the  falling  water.  The  ends  of  a 
concrete  dam  should  extend  well  back  into  the  ditch  banks  on  either 
side  to  prevent  the  water  cutting  around.  Any  such  dam  will  gradually 
allow  the  gully  above  to  fill  with  sediment. 

Dickey  System.  The  use  of  earth  dams  for  filling  large  gullies  is 
very  common  in  some  parts  of  the  state.  A  system  known  as  the 
Dickey  system  has  recently  come  into  some  prominence.  It  consists 
of  a  dam,  usually  of  earth,  at  the  bottom  of  which  is  placed  a  large 
sewer  tile  with  the  upper  end  turned  upward  by  means  of  an  elbow 
joint.  The  water  must  rise  behind  the  dam  to  the  height  of  the  up¬ 
turned  tile  before  it  can  pass  on.  The  sediment  is  largely  deposited  in 
this  standing  water.  Extra  joints  are  then  placed  on  the  upturned 
tile  as  the  dirt  accumulates  until  the  gully  is  entirely  filled.  In  order 
to  remove  the  standing  water  above  the  dam  a  tile  is  often  laid  in  a 
shallow  ditch  made  in  the  bottom  of  the  gully  for  a  short  distance, 
covered  well  to  prevent  washing  out,  and  this  is  then  either  run  into 
the  sewer  pipe  or  thru  the  dam. 

Sewer  of  Good  Size.  The  most  important  point  in  handling  this 
system  of  filling  gullies  is  to  have  the  sewer  large  enough  to  carry 
the  water  of  the  heaviest  rains,  thus  preventing  an  overflow  which 
will  cut  out  the  dam.  Of  course  the  large  reservoir  for  water  above 
the  dam  allows  considerable  storage,  until  the  gully  is  nearly  filled, 
which  decreases  the  danger  of  the  dam  overflowing.  Such  a  system 
is  especially  applicable  to  wide  and  rather  shallow  gullies  such  as 
commonly  occur  near  the  lower  side  of  a  slope  but  it  may  be  used 
on  any  large  gully.  Of  course  where  the  slope  is  steep  and  the  gully 
long,  a  number  of  such  dams  must  be  installed. 

Fill  Hillside  Gully  With  Debris.  For  large  hillside  gullies  it  is 
usually  much  better  to  fill  with  debris  of  various  kinds  and  plow  or 
scrape  in.  Repeated  backfurrowing  over  the  gully  will  gradually  fill  it. 
After  it  is  filled,  cover  heavily  with  manure  and  work  thoroly  into 


12  MISSOURI  AGRICULTURAL  EXPERIMENT  STATION  CIRCULAR  78 

the  surface,  seeding  down  to  grass  with  rye,  oats,  or  other  quick¬ 
growing  cereal  which  will  help  to  hold  the  soil  until  the  grass  gets 
started.  Such  filling  of  large  gullies  is  expensive,  but  it  can  be  done 
if  proper  efforts  are  put  forth.  Land  so  gullied  is  practically  worthless 
and  one  can  afford  to  put  a  large  amount  of  work  into  filling  them. 
Such  a  plan  is  often  followed  in  the  South  with  good  results. 

Plant  Willow  or  Bushes.  The  planting  of  willows  or  bushes  along 
the  edge  of  a  gully  is  often  done  for  the  purpose  of  stopping  further 
erosion.  Where  they  get  a  good  hold  and  a  good  growth  in  the  ditch 
sides  and  bottom,  they  aid  greatly  in  filling  it.  This  planting  is  best 
done  in  late  winter  or  early  spring  and  those  washing  out  should  be 
replaced  until  a  permanent  stand  is  secured. 


